In the known way, a transmission belt drives an external rim of an alternator pulley, driving an internal hub. This pulley is subjected to numerous variations in speed and torque while it is in service, notably because of the non-cyclic nature of the engine. There are various ways of smoothing these variations in speed and torque applied to the pulley, for example by fitting what is known as a one-way clutch (OWC) device, also known as a free wheel, between the hub and the rim. In one direction of rotation, the one-way clutch device transmits the torque from the hub to the rim of the pulley, whereas in the other direction of rotation the pulley operates as a free wheel.
WO-A-2011 079 963 and FR-A-2 726 059 each describe a mechanical system of the pulley type for a motor vehicle alternator, comprising two rolling bearings and a one-way clutch device all arranged between a hub and a rim.
In WO-A-2011 079 963, the rolling bearings are radial-contact ball bearings and their rings are machined. The clutch device comprises cams, and clutch trackways formed directly on the hub and the rim.
In FR-A-2 726 059, the rolling bearings are radial-contact roller or ball bearings. The device comprises clutch trackways which can be formed directly on the hub and the rim. As an alternative, the clutch trackways may be formed on pressed rings which are common to the clutch device and to the rolling bearings. In that case, the multifunctionality of the rings is reduced because these rings cannot be adapted in terms of material, finish, functionality and performance specifically to the clutch device or to the rolling bearings. Moreover, one of the rings has a radial discontinuity forming a means of attachment to the hub. Although the ring becomes easier to position, the axial clearances internal to the system are difficult to control.